@article{1183733579, author = {Levy, Azriel}, title = {On Ackermann's Set Theory}, journal = {J. Symbolic Logic}, volume = {24}, number = {1}, year = {1959}, pages = { 154-166}, language = {en}, url = {http://dml.mathdoc.fr/item/1183733579} }
Levy, Azriel. On Ackermann's Set Theory. J. Symbolic Logic, Tome 24 (1959) no. 1, pp. 154-166. http://gdmltest.u-ga.fr/item/1183733579/